Observing Mixtures and Solutions

In this investigation, you will…•Make mixtures and solutions with different solid materials and water•Separate mixtures and solutions using screens, filters, and evaporation•Measure solids and liquids•Compare the mass of a mixture to the mass of its parts.

Investigation 1:

Part 1

Making and Separating Mixtures

Three solid materials

• Gravel (Labeled on cup as G)

• Powder (labeled on cup as P)

• Salt (sodium chloride) (labeled on cup as S)

Observations of materials

• Each group will get 1 spoon of each of the solid material and use seeing, hearing, smelling, and touching to describe each material.

• Please remember that you are never to taste any of the materials

What do you observe?

1) Gravel

2) Powder

3) Salt

Record your observations on your student sheet

What do you think might happen if you add water to each cup containing the dry materials?

Your materials

• Screen

• Funnel

• Sticks

• Filter paper

• Syringe

• Hand lenses

Making a mixture

1. Use the syringe to put 50 ml of water into each cup

2. Stir the contents with a stick

3. Observe what happens and record it on your student sheet

What is a mixture?

A mixture is two or more substances that’s mixed together; but can be separated out two or more because their atoms aren’t combined.

What are some mixtures you use in everyday life?

Mixtures can always be seperated

How can we separate our 3 mixtures?Our goal is to separate the mixtures so

that the water is in one cup and the solid material is in another.

Gravel and water mixture- Screen

1) Take both of your G cups and your screen

2) Stir the gravel and water mixture thoroughly

3) Place the empty G cup flat on the desk, put the screen on top and pour the mixture through the screen

4) Try to separate other two mixtures using the screen

Filter paper- fine mesh screen with holes so small they can’t be seen with the naked eye.

Filter paper is a fine mesh screen with holes so small, it can’t be seen with the naked eye.

Demo of how to set up filter paper1) Fold paper in quarters

2) Open it to make a cone

Remember to stir mixture before attempting to filter and to use a separate filter for each filter.

Go ahead and try to filter your powder mixture and then your salt mixture.

Which mixture was separated by the paper filter?

Powder and water

How are a screen and filter paper similar? How are they different?

Both separate materials, but one has finer holes.

What about the salt and water mixture?

If the solid material in a mixture seems to disappear in a liquid, and the mixture can’t be separated from the water with a filter, it is a special kind of mixture called a solution.

Salt disappears or dissolves in water to make a saltwater solution.

What Is A SolutionWhat Is A SolutionA solution is a special kind of A solution is a special kind of mixture. Most solutions are made mixture. Most solutions are made by a solid and a liquid. When a by a solid and a liquid. When a solid dissolves in a liquid, the solid dissolves in a liquid, the liquid becomes the solvent and liquid becomes the solvent and the solid becomes the solute.the solid becomes the solute.

Vocabulary

• Solution- A special kind of mixture formed when one or more materials dissolved in another compound.

• Liquid- A form of matter of matter that can flow freely and take the shape of the container.

• Mixture-two or more substances that are mixed but can be separated because their atoms aren’t physically joined.

• Dissolving- the process of a material becoming incorporated informing into another.

• Property- a characteristic of an object, something you can observe such as size, color, shape, or texture.

Classifying A Mixture

Solute- A substance that dissolves in a solvent to form a solution.

Solvent-A substance in which another substance is dissolved.

Example: saltwatersolvent: water Solute: salt3 kinds of mixtures:Solid/solidSolid/liquidliquid/solid

Let’s Review

What is a mixture? Examples What is a solution? examples

What did I learn?

A mixture combines two or more materials that retain their own properties

A solution forms when a material dissolves in a liquid (solvent) and cannot be retrieved with a filter

Investigation 1Part 2

Separating a salt solution

Review

• What is a mixture?• How can a mixture be separated?• Can you separate a solution with a

screen? With a filter paper?• How might you separate the

ingredients in a solution?

Demo of how to weigh 50 ml of water1) Put two cups on the balance and zero

the balance2) Use a syringe to put 50 ml of water in

one cup3) Use the 1g pieces, add gram pieces

until balance is achieved4) Count the gram pieces.5) What is the mass?

Will a solution made with 50 ml of water and a spoon of salt have the same mass as 50 ml of plain water? More mass? Less mass? How can you find out?

How can you determine the number of grams of salt you put in the water to make the solution?

• Remember the mass of 50 ml is 50g

Evaporate the salt solution

• You separated the gravel from the water

• You separated the powder from the filter

• How can you separate the salt from the water? How can you get the salt back

Reading/Wrap-up

• Mixtures and Solutions• Compete student sheets• Save evaporating dishes for next

time

How to separate a mixture and a solution

• Picking• Sifting • Evaporation• Filtering

What did I learn?

• Evaporation can separate a liquid from a solid in a solution

Investigation 1

Part 3Observing Crystals

Record observations

• What happened when the saltwater solution evaporated?

• What is the material in the dish?• What happened to the water that

was in the mixture?• Does the salt look the same as it

did originally?

What is a crystal?

• A crystal is a solid form of a material that can be identified by its properties, such as shape, color, and patterns. The salt unit is square with an X corner to corner.

Review

How would you separate…• Gravel and water mixture• Powder and water mixture• Salt and water solution

Vocabulary

• Evaporation- causes liquids to dry up- the liquid turns to gas and disperses into the air, leaving any dissolved solid material behind

• Crystal- the solid form of a material that can be identified by its properties, such as shape, color, and pattern

Wrap-up

• Complete student sheets• Read A Salty Story

What did I learn?

• The solid material separated by evaporation from a solution forms distinctive, unique patterns

Investigation 4

Part 4Separating a dry mixture

Making a dry mixture

• Put one ml of gravel, powder, and salt in the container and stir

• Your challenge is to design a method to separate this mixture of three solid materials so that the gravel ends up in the G cup, the powder in the P cup, and the salt in the S cup

Plan your attack

• Take some time and plan how you will separate the dry mixture

• Write your plan on your student sheet

Separating a dry mixture

• Has your group separated the gravel?

• Has your group separated the powder?

• Has your group separated the salt?

Clean-up/wrap-up

• Cleanup• Read science stories called Earth

Elements